Power requirement for 3 GPU's not in SLI (VMware)

I'm setting up a single physical computer, with the purpose of three people having their own Windows VM's to run games and web browse. Since I don't believe there is a way to share one GPU among 3 VM's (without Nvidia GRID) I plan on installing three GTX 950 cards. Based on the "power requirements for graphics cards" for the GTX 950, I estimate power usage at 620 watts for total system power.

My question: Will the power requirements be the same for three cards working individually, versus if the cards were in SLI?

Optional question: Anyone know a way to share a single gaming GPU among 2 or more VM's?